US4768878A - Test arrangement for non-contacting identification of defects in non-structured surfaces - Google Patents

Test arrangement for non-contacting identification of defects in non-structured surfaces Download PDF

Info

Publication number
US4768878A
US4768878A US06/905,186 US90518686A US4768878A US 4768878 A US4768878 A US 4768878A US 90518686 A US90518686 A US 90518686A US 4768878 A US4768878 A US 4768878A
Authority
US
United States
Prior art keywords
diaphragm
edges
light
test arrangement
arrangement according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US06/905,186
Other languages
English (en)
Inventor
Wolfgang Heine
Walter Huber
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Assigned to SIEMENS AKTIENGESELLSCHAFT, A GERMAN CORP reassignment SIEMENS AKTIENGESELLSCHAFT, A GERMAN CORP ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: HEINE, WOLFGANG, HUBER, WALTER
Application granted granted Critical
Publication of US4768878A publication Critical patent/US4768878A/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/89—Investigating the presence of flaws or contamination in moving material, e.g. running paper or textiles
    • G01N21/8901—Optical details; Scanning details

Definitions

  • the present invention is directed to a test arrangement for non-contacting identification of defects in a non-structured surface.
  • the test arrangement includes means for generating a scanning light ray, means for directing the light ray onto a non-structured surface, means for collecting light deflected at a defective location including an opto-electronic receiver for the detection of the collected light.
  • the surface of the unit under test which is to be investigated, is scanned with a laser beam.
  • the relative motion between the laser beam and the unit under test required for this purpose is thereby usually generated in the first direction by a scanning mirror arranged in the beam path and is generated in the second direction perpendicular to the first direction by displacing the unit under test.
  • the laser beam strikes a defective location, then the light is scattered or, respectively, defracted and can be detected as either reflected light or transmitted light via an opto-electronic receiver which supplies a signal corresponding to the detected defect.
  • a hemisphere acting on the principle of Ulbricht's sphere is used, for example, as an optical collecting means and the hemisphere integrates the individual light rays coming from a defective location and thus, fully acquires them via the inside surface of the hemisphere.
  • many other shapes standard for optical collecting elements such as elliptical hollow members, ellipsoids, parabolic hollow members of paraboloids and the like can be utilized.
  • the laser beams employed as the scanning light ray has a relatively large halo, which in particular is attributed to light scatter of lenses, mirrored surfaces and the laser itself. This halo then causes unfavorable signal-to-noise ration so that smaller defects can no longer be reliably identified.
  • the object of the present invention is to create a test installation for non-contact identification of defects in non-structured surfaces with which even the smallest defect having dimensions in sub-micrometer range can be reliably identified.
  • testing arrangement for non-contact identifying of defects in non-structured systems
  • said testing arrangement including a means for generating a scanning light ray, means for directing the scanning light ray on the surface being tested, means for collecting light deflected at a defective location of the surface including an opto-electronic receiver for the detection of the collected light.
  • the means for directing the scanning light ray on the surface includes a positioning of a diaphragm for reducing the light scatter components in the beam path of the scanning light ray, said diaphragm having at least two diaphragm edges being successively arranged in the diaphragm so that every following diaphragm edge at least partially blocks the light defracted into a shadow space of the preceding diaphragm edge.
  • the invention is based on the perception that the light scatter components of the scanning light ray can be reduced to such a degree by means of a diaphragm inserted into the beam path that due to the corresponding improved signal-to-noise ratio, even the smallest defect in the sub-micrometer range can be reliably acquired.
  • the prerequisite for such an effect of the diaphragm is that it thereby comprises at least two, preferably a plurality, of diaphragm edges arranged following one another so that every following diaphragm edge at least partially acquires or blocks the light defracted into the shadow space by the preceding diaphragm edge. Given such an arrangement, the defracted light is thus, reduced further with every diaphragm edge as seen in the direction of the scanning light rays so that the light beam profile of the scanning light beam is modified in the direction towards a rectangular shape.
  • the diaphragm edges are arranged following one another such that every following diaphragm edge cuts the first secondary maximum of the light defracted into the allocated shadow space by the preceding diaphragm edge. A particularly great part of the light scatter is rendered ineffective by means of such a cut-out of the secondary maximums.
  • the diaphragm edges are preferably fashioned as sharp knife edges whereby the reflecting surface of the diaphragm edges in the component of the light reflected at them are reduced.
  • the region of the diaphragm lying between the diaphragm edges comprise a light absorbing surface so that the light defracted into the shadow space is absorbed and can thus, be rendered ineffective.
  • the diaphragm is expediently arranged following the deflection means as seen in the direction of the scanning light ray.
  • the diaphragm can then also block the light scatter generated by the deflecting means, for example, a scanning mirror, and can reduce it or, respectively, neutralize it.
  • the diaphragm edges are then preferably aligned parallel to the deflection plane of the scanning light ray so that the passage of the light component desired for the scanning is not impeded.
  • the inverse product of the scanning light ray can then have additional diaphragm edges of the diaphragm allocated to them so that the light scatter component can also be reduced in the region of these reversal points in the path of the light.
  • the diaphragm edges are formed by a saw-toothed profile on the side wall of the diaphragm which side walls lie opposite to one another.
  • the manufacture of the diaphragm is considerably simplified and a fixed relative position of the diaphragm edge on a side wall is guaranteed.
  • a plurality of diaphragm edges can be accommodated in a tiny space by means of the saw-toothed profiles.
  • the diaphragm edges are then preferably arranged offset relative to the additional diaphragm edges so that the diaphragm edges in the additional diaphragm edges can engage into one another in the corner region of the diaphragm without disturbing one another.
  • the effect of the diaphragm can be optimized in a simple way by means of an appropriate adjustment.
  • the width of the diaphragm gap formed by the first diaphragm edge at least approximately corresponds to the diameter of the scanning light ray.
  • the rays defracted into the light space by the diaphragm edges can pass through the diaphragm when they are steeper than the diagonal between the first and the last diaphragm edges.
  • the diaphragm angle should therefore be kept as small as possible. This is achieved by means of an appropriate dimensioning with the spacing between the first diaphragm edge and the last diaphragm edge corresponding to at least ten times the value of the diameter of the standing light ray. Preferably, this distance or spacing is at least in a range of 100 through 200 times the value of the diameter of the scanning light ray.
  • FIG. 1 is a schematic illustration of a test installation for non-contact identification of defects in a non-structured surface in accordance with the present invention
  • FIG. 2 is a side view of the diaphragm employed in the test arrangement of FIG. 1 with a portion removed for purposes of illustration;
  • FIG. 3 is an enlarged partial cross sectional view of the diaphragm edges of the diaphragm of FIG. 2;
  • FIG. 4 is a graph illustrating the light intensity relative to the diameter for the beam profile of the scanning light beam.
  • FIG. 5 is a beam profile of the intensity to the beam diameter of the beam after it has passed through the diaphragm of the present invention.
  • the principles of the present invention are particularly useful when incorporated in a test installation which is schematically illustrated in the FIGS.
  • the test installation is for non-contacted identification of defects D in a non-structured surface F of a unit P.
  • the arrangement or installation includes means E1 for generating a scanning ray As. As the light leaves the light generating means E1, it passes through an expanding optics Ao then to a focussing optics Fo to a deflecting means Ae which deflects it through a diaphragm B for reducing the light scatter components of the beam.
  • the scanning light ray As is periodically moved back and forth by the deflecting means Ae in a direction indicated by the double arrow Z, which is in the plane of the drawings, due to the rotation of the deflecting means Ae as indicated by the double arrow Dpf.
  • the light will extend through a slit in a means E2 to strike the surface F, which is to be investigated, of the unit P under test.
  • the unit P is dislocated in a direction perpendicular to the plane of the drawings so that the surface F is scanned by the scanning light rays.
  • the unit P can also be moved with a meandering-shaped path when requested.
  • the scanning light rays As impinge faultless regions of the surface F then the light is in the reflected direction again leaves the means E2 through the slit through which it is entered.
  • a defect D which can be a pore on the surface F, an inclusion of a foreign body, a contamination of the surface or the like, then the light is scattered and defracted and the corresponding scattered lobe is reference Sk.
  • the light scattered and defracted at the defect location is then at least partially collected by the means E2 and directed or collected into light sensitive surfaces of an electro-optical receiver E whose output signal S indicates the detected defect D.
  • the means E1 is preferably a laser, for example, a HeCd laser, whose emmission is expanded to a diameter of 4 mm and the expanding optics Ao from an initial diameter of 1 mm.
  • the expanding laser beam is then focussed onto the surface F by the focussing optics Fo so that the diameter of the beam at the point of incidence amounts to 50 ⁇ m.
  • the diaphragm B comprises two side walls Sw and two end walls Ew.
  • the position inclination of the two end walls is matched to the maximum excursion of the scanning light ray As.
  • the two side walls Sw are arranged shortly before or, respectively, following the deflection plane of the scanning rays As and lie in the plane of the drawing. Further details regarding the structure and the functioning of the diaphragm B are set forth later with reference to FIGS. 2-5.
  • the means E2 for collecting light deflected at the deflecting location is a hemisphere opened towards the bottom which is arranged above the surface F of the unit P under test.
  • the hemisphere is painted matte white on the inside so that the light scattered and defracted at the deflected defect D is repeatedly and diffusedly reflected so that every surface element on the inside surface of the hemisphere is illuminated to approximately the same degree.
  • the light rays coming from the defect D are acquired and one partially supplied to the light sensitive surface of the electro-electronic receiver E, which may be, for example, a photo-multiplier and this receiver lies in the region of the inside surface of the hemisphere.
  • the diaphragm B is illustrated in FIG. 2 with a front end wall Ew removed.
  • the insides of the side walls Sw are provided with saw-toothed-shaped profiles by means of which the diaphragm edges Bk1, Bk2, . . . , Bkn are provided and lie opposite each other at the same height. As illustrated, n equals 30.
  • the diaphragm edges Bk1 through Bkn proceed towards the back perpendicular to the plane of the drawings and form diaphragm gaps whose width b1-bn increase in the direction of the scanning light ray As passing through the diaphragm B.
  • Each of the end walls Ew has a saw-toothed-shaped profile of diaphragm edges Bkz1 . .
  • Bkzn and the inside wall surfaces of the two end walls Ew are inclined at an angle relative to one another. These additional diaphragm edges Bkz1 through Bkzn are allocated to the reversal point of the scanning light rays As and are offset relative to the diaphragm edges Bk1 through Bkn so that no mutual impediment can occur in the corner regions of the diaphragm B when all the walls are assembled together. As illustrated, the walls can be assembled together and displaced in an adjustable fashion with the two side walls Sw being offset relative to the two end walls Ew.
  • the two side walls Sw and the two end walls Ew are composed of aluminum and the profiles on the inside surfaces are respectively anodically oxidized to a matte black.
  • the width b1 of the diaphragm gap formed by the first diaphragm edges Bk1 preferably corresponds to the diameter d of the scanning light ray As indicated by arrows and amounts to 1 mm in the illustrated examplary embodiment.
  • the width bn of the diaphragm gap for by the last diaphragm edge Bkn by contrast amounts to 1.5 mm.
  • the spacing or distance 1 between the first diaphragm edges Bk1 and the last diaphragm edges Bkn is preferably of a value of at least 10 times the diameter d of the scanning light ray As.
  • the spacing 1 falls in a range of at least 100-200 times the value of the diameter d for the scanning light rays As.
  • the principles of the functioning of the diaphragm B is best illustrated in FIG. 3; however, only three diaphragm edges Bk1, Bk2 and Bk3 are illustrated.
  • the first diaphragm edge Bk1 forms a diaphragm gap having a width of b1 whose light space is referenced Lr1 and whose shadow space is reference Sr1.
  • the second diaphragm edge Bk2 forms a diaphragm gap having a width b2 whose light space is referenced Lr2 and whose shadow space is Sr2.
  • the third diaphragm edge Bk2 forms a diaphragm gap having a width b3 whose light space is referenced Lr3 and whose shadow space is Sr3.
  • the width b1 of the diaphragm gap formed by the first diaphragm edge Bk1 is dimensioned so that it is at least approximately identical to the diameter d of the scanning light rays As.
  • the first diaphragm edge Bk1 then defracts the light both into a shadow space Sr1 as well as into a light space Lr1.
  • the second diaphragm edge Bk2 is now arranged so that in the shadow space Sr1 it will cut or block the first secondary maximum of the light which the first diaphragm edge Bk1 deflects into the allocated shadow space Sr1.
  • the second diaphragm edge Bk2 then again defracts both into the allocated shadow space Sr2 as well as into the allocated light space Lr2.
  • the third diaphragm edge Bk3 is then arranged so that it will cut or block the first secondary maximum of the light which was defracted by the second diaphragm edge Bk2 into the allocated shadow space Sr2. It may be seen that the defracted light is continuously reduced in the direction of the scanning light rays As and thus, the halo of the scanning light rays As is reduced further and further.
  • the resulting bell curve of Gaussian distribution curve is referenced Gk where as the undesired light scatter components of the scanning light ray As are indicated by the curve branches St.
  • the beam cross section Sq ⁇ d 2 /4 wherein d is the forementioned diameter of the scanning light ray.
  • the intensity of the scanning light ray As after exit from the diaphragm B is plotted against the beam cross section Sq and produces a curve K of FIG. 5. It may be seen that the effect of the diaphragm B and the shadowing of the light scattering laterally cuts or clips the typical bell-shaped curve Gk of FIG. 4 and the resulting curve K approaches a rectangular shape R indicated in dot-dash lines.
  • the halos of the scanning light ray As is at least largely eliminated by the action of the diaphragm B.
  • a signal-to-noise ratio of the test installation shown in FIG. 1 is improved so that even extremely small defects having a dimension in the sub-micrometer region can be reliably detected.

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
US06/905,186 1985-09-09 1986-09-09 Test arrangement for non-contacting identification of defects in non-structured surfaces Expired - Fee Related US4768878A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3532117 1985-09-09
DE3532117 1985-09-09

Publications (1)

Publication Number Publication Date
US4768878A true US4768878A (en) 1988-09-06

Family

ID=6280467

Family Applications (1)

Application Number Title Priority Date Filing Date
US06/905,186 Expired - Fee Related US4768878A (en) 1985-09-09 1986-09-09 Test arrangement for non-contacting identification of defects in non-structured surfaces

Country Status (3)

Country Link
US (1) US4768878A (de)
EP (1) EP0218865B1 (de)
DE (1) DE3667855D1 (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5135303A (en) * 1990-02-20 1992-08-04 Hitachi, Ltd. Method of and apparatus for inspecting surface defects
US5155777A (en) * 1991-06-26 1992-10-13 International Business Machines Corporation Scattered light blocking layer for optoelectronic receivers
US5309339A (en) * 1992-06-24 1994-05-03 The Schepens Eye Research Institute, Inc. Concentrator for laser light
US5402001A (en) * 1992-10-05 1995-03-28 Matsushita Electric Industrial Co., Ltd. Method of checking for foreign matter on a substrate with light of maximum reflectivity for that substrate
US5444265A (en) * 1993-02-23 1995-08-22 Lsi Logic Corporation Method and apparatus for detecting defective semiconductor wafers during fabrication thereof
US20040239919A1 (en) * 2003-04-30 2004-12-02 Byk Gardner Gmbh Device and method for determining the properties of surfaces

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8916033D0 (en) * 1989-07-13 1989-08-31 De La Rue Syst Sheet inspection apparatus
FR2681133A1 (fr) * 1991-09-11 1993-03-12 Languedoc Verrerie Dispositif d'emission ou d'absorption de lumiere pour le controle sans contact d'objets.

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2422273A (en) * 1942-11-28 1947-06-17 Brown Instr Co Lens type radiation pyrometer
DE1473681A1 (de) * 1965-11-17 1969-02-06 Agfa Gevaert Ag Verfahren zur optischen Fehlersuche,besonders an grossflaechigen Materialien
US3917414A (en) * 1973-10-11 1975-11-04 Geisco Associates Optical inspection system
US4175865A (en) * 1976-04-05 1979-11-27 Cerberus Ag Smoke detector
FR2477288A1 (fr) * 1980-03-03 1981-09-04 Vidal Bernard Piege a lumiere a discrimination angulaire
US4378159A (en) * 1981-03-30 1983-03-29 Tencor Instruments Scanning contaminant and defect detector
JPS59208408A (ja) * 1983-05-13 1984-11-26 Toshiba Corp 表面検査方法及びその装置
US4601576A (en) * 1983-12-09 1986-07-22 Tencor Instruments Light collector for optical contaminant and flaw detector
EP0146005B1 (de) * 1983-11-26 1991-08-28 Kabushiki Kaisha Toshiba Apparat zum Nachweis von Oberflächenfehlern

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2422273A (en) * 1942-11-28 1947-06-17 Brown Instr Co Lens type radiation pyrometer
DE1473681A1 (de) * 1965-11-17 1969-02-06 Agfa Gevaert Ag Verfahren zur optischen Fehlersuche,besonders an grossflaechigen Materialien
US3917414A (en) * 1973-10-11 1975-11-04 Geisco Associates Optical inspection system
US4175865A (en) * 1976-04-05 1979-11-27 Cerberus Ag Smoke detector
FR2477288A1 (fr) * 1980-03-03 1981-09-04 Vidal Bernard Piege a lumiere a discrimination angulaire
US4378159A (en) * 1981-03-30 1983-03-29 Tencor Instruments Scanning contaminant and defect detector
JPS59208408A (ja) * 1983-05-13 1984-11-26 Toshiba Corp 表面検査方法及びその装置
EP0146005B1 (de) * 1983-11-26 1991-08-28 Kabushiki Kaisha Toshiba Apparat zum Nachweis von Oberflächenfehlern
US4601576A (en) * 1983-12-09 1986-07-22 Tencor Instruments Light collector for optical contaminant and flaw detector

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5135303A (en) * 1990-02-20 1992-08-04 Hitachi, Ltd. Method of and apparatus for inspecting surface defects
US5155777A (en) * 1991-06-26 1992-10-13 International Business Machines Corporation Scattered light blocking layer for optoelectronic receivers
US5309339A (en) * 1992-06-24 1994-05-03 The Schepens Eye Research Institute, Inc. Concentrator for laser light
US5402001A (en) * 1992-10-05 1995-03-28 Matsushita Electric Industrial Co., Ltd. Method of checking for foreign matter on a substrate with light of maximum reflectivity for that substrate
US5444265A (en) * 1993-02-23 1995-08-22 Lsi Logic Corporation Method and apparatus for detecting defective semiconductor wafers during fabrication thereof
US20040239919A1 (en) * 2003-04-30 2004-12-02 Byk Gardner Gmbh Device and method for determining the properties of surfaces
US7460218B2 (en) * 2003-04-30 2008-12-02 Byk Gardner Gmbh Device and method for determining the properties of surfaces

Also Published As

Publication number Publication date
DE3667855D1 (de) 1990-02-01
EP0218865B1 (de) 1989-12-27
EP0218865A1 (de) 1987-04-22

Similar Documents

Publication Publication Date Title
US4601576A (en) Light collector for optical contaminant and flaw detector
KR100322326B1 (ko) 인렌즈오프엑시스조사기를갖는검사시스템
KR100669845B1 (ko) 표면 상의 이상을 검사하기 위한 스캐닝 방법 및 시스템
KR100228026B1 (ko) 이물질 검사를 위한 방법 및 장치
US4523841A (en) Radiant energy reradiating flow cell system and method
JPS632459B2 (de)
WO1997012226A1 (en) Improved system for surface inspection
US5153428A (en) Confocal laser scanning microscope having relay lens and a slit for removing stray light
US7205518B2 (en) Method and arrangement for focusing in an optical measurement
CA1135971A (en) Radiant energy reradiating flow cell system and method
US4522497A (en) Web scanning apparatus
JPS6223250B2 (de)
US4768878A (en) Test arrangement for non-contacting identification of defects in non-structured surfaces
US3675016A (en) Flying spot scanning
US4330205A (en) Optical apparatus for measuring the size and location of optical in an article
JPH06160288A (ja) 検出装置、特に紙巻き煙草の表面検査をするための装置
US4116566A (en) Line scanning device for detecting defects in webs of material
US5162645A (en) Photographic scanner with reduced susceptibility to scattering
JPS6273143A (ja) 光学式ウエブ監視装置
JPS638420B2 (de)
US7245366B2 (en) Surface inspection method and surface inspection apparatus
JP3185878B2 (ja) 光学的検査装置
EP0018505A2 (de) Apparat zur Überwachung des Zustandes von Banknoten
US4736099A (en) Scan device with light mixer and diffusing means for half-tone transparency originals
EP0244102B1 (de) Vorrichtung zur Güteprüfung

Legal Events

Date Code Title Description
AS Assignment

Owner name: SIEMENS AKTIENGESELLSCHAFT, BERLIN AND MUNICH, A G

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:HEINE, WOLFGANG;HUBER, WALTER;REEL/FRAME:004603/0238

Effective date: 19860829

Owner name: SIEMENS AKTIENGESELLSCHAFT, A GERMAN CORP, GERMANY

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HEINE, WOLFGANG;HUBER, WALTER;REEL/FRAME:004603/0238

Effective date: 19860829

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
FP Lapsed due to failure to pay maintenance fee

Effective date: 19920906

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362